1. Field of the Invention
The present invention relates to a soundproof type engine driven work machine (hereinafter referred to as work machine), and more particularly relates to a construction of introducing the cooling air into a soundproof casing accommodating an engine driven work machine unit.
2. Prior Art
A work machine unit accommodated within a soundproof casing has been conventionally used to reduce uncomfortable noise. A soundproof type engine driven generator (hereinafter referred to as generator) is explained as a typical example of this kind of work machines.
As shown in FIG. 1, main part of the generator comprises a generator unit Gxe2x80x3 as a work machine unit, an engine Exe2x80x3  of which rear end power axis is communicated to the generator unit Gxe2x80x2, a muffler Mxe2x80x3 connecting to the engine Exe2x80x3, an air-cooled type inter-cooler Ixe2x80x3 acting as a charge cooler, and a radiator Rxe2x80x3. An engine fan Fxe2x80x3 is directly provided to the front end of said engine Exe2x80x3 and driven by said engine E. Directly opposite to said engine fan Fxe2x80x3 the inter-cooler Ixe2x80x3 and the radiator Rxe2x80x3 are aligned in consecutive order from right to left in FIG. 1. All abovementioned parts are accommodated in a soundproof casing Kxe2x80x3 to reduce uncomfortable noise. There are provided an air intake aperture 31axe2x80x3 on the rear side of said soundproof casing K and an air exhaust aperture 25axe2x80x3 on the ceiling at front side.
While said generator being driven, the heat generated from the generator unit Gxe2x80x3, the engine Exe2x80x3, the inter-cooler Ixe2x80x3, the radiator Rxe2x80x3 and the muffler Mxe2x80x3 is cooled by the cooling air flowing through the soundproof casing K. The cooling air is introduced into the soundproof casing K through the air intake aperture 31axe2x80x3 by rotating the engine fan Fxe2x80x3. The cooling air passes through an air flow passage formed in the soundproof casing K consecutively as cooling the generator unit Gxe2x80x3, the engine Exe2x80x3, the inter-cooler Ixe2x80x3, the radiator Rxe2x80x3 and the muffler Mxe2x80x3 and is exhausted through the exhaust aperture 25a. 
However, it has been pointed out that the cooling air is warmed up because it goes through the intake aperture 31axe2x80x3, the generator unit Gxe2x80x3, the engine Exe2x80x3, the inter-cooler Ixe2x80x3, the radiator Rxe2x80x3 and the muffler Mxe2x80x3 while passing through the soundproof casing K, the cooling air is warmed up by the heat of the air already cooled the aforementioned apparatuses. As the cooling air approaches the exhaust aperture 25a said cooling air to cool the inter-cooler Ixe2x80x3, the radiator Rxe2x80x3 and the muffler Mxe2x80x3 is already warmed up. Thus, the cooling efficiency is much reduced.
In order to overcome such undesirable efficiency reduction it is naturally required to supply more additional cooling air into the soundproof casing K so that the cooling air may cool the inter-cooler Ixe2x80x3, the radiator Rxe2x80x3 and the muffler Mxe2x80x3 sufficiently. In other word, it was required to enlarge the areas of the intake aperture 31axe2x80x3 and the exhaust aperture 25axe2x80x3 or expand the capacities of the radiator Rxe2x80x3, the inter-cooler Ixe2x80x3 and the engine fan Fxe2x80x3.
In the meantime, the conventional generator in which the inter-cooler Ixe2x80x3 and the radiator Rxe2x80x3 are provided opposite to the engine fan Fxe2x80x3 is pointed out that the combustion sound of the engine Exe2x80x3 or the machine sound (hereinafter referred to as engine sound) which is the main cause of the engine sound is leaked outside through the air intake aperture 31axe2x80x3 or the air exhaust aperture 25a after passing through the core part of the radiator Rxe2x80x3.
For this reason, if the area of the air intake aperture 31axe2x80x3 or the air exhaust aperture 25axe2x80x3 should be enlarged, the engine sound during the operation of the generator is accordingly much enlarged. Meanwhile, if the capacities of the inter-cooler Ixe2x80x3 and the radiator Rxe2x80x3 are enlarged, a more larger inter-cooler Ixe2x80x3 and a more larger radiator Rxe2x80x3 are required and thus the dimension of the core part is enlarged and the engine sound passing through the said core part becomes larger. The engine sound becomes larger more and more. This is a big problem of the engine sound.
In the meantime, to reduce the leakage of the noisy sound from the soundproof casing Kxe2x80x3, it is required to reduce the areas of the aperture of the air intake aperture 31axe2x80x3 and the air exhaust aperture 25axe2x80x3. Further it is required to provide an element to shut the transmission of the noisy sound in the cooling air passages in the casing K or to provide some bending parts in the passages to obstruct the pressure is also required. However, against such construction, it is pointed out that the volume of the cooling air is reduced and cooling efficiency at each apparatus is reduced.
Accordingly, improving the cooling efficiency and reducing the noisy sound at each apparatus conflict with each other.
Furthermore, if the volumes of the inter-cooler Ixe2x80x3, the radiator Rxe2x80x3, the engine fan F, etc. are enlarged, the configuration dimension of the soundproof casing K which accommodates these apparatuses is accordingly enlarged. This will be in conflict with the concept that the size of the generator should be small.
The present invention has been made with the foregoing background in mind. The object of the present invention is to offer a soundproof type engine driven work machine to improve the cooling efficiency and reduce the noise.
In order to resolve the foregoing detects, the soundproof type engine driven work machine according to the present invention is provided with an engine with an engine fan, a work machine unit driven with said engine, a radiator connected to the engine, a charge cooler and the muffler. These apparatuses are accommodated in the soundproof casing. The soundproof casing is divided to an engine room, a muffler room and a radiator room in which said engine as well as said work machine unit being housed in the engine room, said muffler being housed in said muffler room and said radiator being housed in said radiator room. Said engine room is provided with the air intake aperture, said muffler room being provided with the air exhaust aperture, said radiator room being provided with the air intake aperture, respectively. Said radiator room and said muffler room are communicated each other. An electric fan is provided between said air intake aperture in the radiator room and said radiator. Further, an air flow duct is provided between said engine room and said muffler room. The engine fan is provided directly opposite to an inlet of the air flow duct. In the air flow duct there is provided said charge cooler. This is the main characteristic of the soundproof type engine driven work machine according to the present invention.
The charge cooler indicates an apparatus to cool the air for combustion the engine which has been supercharged by compression. It indicates an inter-cooler or an after cooler apparatuses.
The air intake aperture and the air exhaust aperture formed in each room introduces and exhausts the air through each aperture, respectively.
Accordingly, the soundproof casing is divided to the engine room, the muffler room and the radiator room. The engine room encloses the engine and the work machine unit, the muffler room encloses the muffler and the radiator room encloses the radiator, respectively. The radiator room is provided with the electric fan and the air flow duct is provided with the air-cooling apparatus. Thus, cooling efficiency for the apparatus in each room is greately improved.
In radiator room, a clear non-heated air introduced from outside through the air intake aperture by means of electric fan is used for cooling said electric fan and the cooling air only used for cooling the electric fan is used for cooling the radiator. Thus cooling efficiency is greately improved.
The cooling air in the engine room and the air flow duct for cooling the work machine unit, the engine and the charge cooler is sucked from the air intake aperture of the engine room by means of the engine fan provided in the engine. The cooling air travels from the work machine unit and the engine and is introduced to the air flow duct to cool the charge cooler. Further, after passing through the muffler room and the engine room, the muffler is cooled by the air introduced from the air flow duct, or the cooling air introduced from the radiator room. The cooling air used is not the air used for cooling all of the engine, the charge cooler and the radiator. Thus cooling efficiency is improved.
Further, cooling of the radiator is not required; it becomes possible to decrease the amount of the cooling air. Thus, the size of the engine fan can be reduced. Like that, as necessary amount of the cooling air for cooling each apparatus is decreased, smaller size of engine is available when compared with the conventional apparatus. Areas of the air intake aperture and the air exhaust aperture can be reduced. Also, it is possible to place an element to prevent noise propagation in air flow passage, or to provide a bent to disturb the inside pressure. It is possible to decrease the noise leaking out to the exterior of the soundproof casing.
Further, the size of the electric fan can be reduced because it cools only the radiator efficiently with aligned flow of the cooling air. The wind-cut noise from the core of the radiator is reduced. The noise is also greately reduced by preventing it from leaking out through the air intake aperture by means of the electric fan.
As the muffler room and the radiator room are communicated, if the electric fan in the radiator room should be stopped due to some unknown reasons, the cooling air is introduced from the muffler room to the radiator room by closing the exhaust aperture of the muffler room, the cooling air is exhausted through the air intake aperture of the radiator room after cooling the radiator. For this reason, the generator is continuously operated under the lower load operating condition.
Further, the present invention is characterized in that an air exhaust aperture of the muffler room is provided at the ceiling part of the soundproof casing of the soundproof type engine driven work machine.
Accordingly, the exhaust air of the muffler room and the exhaust air of the radiator room are exhausted from the air exhaust aperture of the muffler room provided at the ceiling of the soundproof casing. The air absorbs the heat of the engine, the charge cooler and the muffler, or the heat of the radiator. The heated air goes upward and is exhausted through the air exhaust aperture. The air exhaust efficiency is greately improved. The noise from the air exhaust aperture is diffused upward above the ceiling of the soundproof casing. Thus, the unfavorable noise near the work machine is particularly reduced.